Thinkpad X1 Carbon Gen7 not charging

Hi,

I have a 3.5 year old (so warranty expired 6 months ago, of course) Lenovo Thinkpad X1 Carbon Gen7. Since yesterday it is no longer charging when plugged in. It still sits at 95%, but it has always been charging up to 100%. The little white LED next to the power jack lights up when connected. It's a dual boot Ubuntu/Windows setup, and I have the same issue in both OS:es.

What I have tried, to no avail:

* Turning off and holding power key for 30+ seconds, and then booting. * Pressing the pinhole reset button while powered off. * Installing latest bios and Lenovo drivers. * Moving the power cable to the second charging jack. * Checked the condition of the battery in Lenovo Vantage - "Battery is in good condition". * EDIT: Also tested with my phone charger instead, but that one is obviously only max 18 W compared to Lenovo's 65 W. Will try to use a different charger when I can, but since the laptop seems to be working fine on the power cord I don't think that is the issue.

What else can I do? Is this a hardware or a software issue? Should I order a replacement battery or will this fix nothing?